1 // Copyright 2012 Google Inc. All Rights Reserved.
2 //
3 // Use of this source code is governed by a BSD-style license
4 // that can be found in the COPYING file in the root of the source
5 // tree. An additional intellectual property rights grant can be found
6 // in the file PATENTS. All contributing project authors may
7 // be found in the AUTHORS file in the root of the source tree.
8 // -----------------------------------------------------------------------------
9 //
10 // Misc. common utility functions
11 //
12 // Authors: Skal ([email protected])
13 // Urvang ([email protected])
14
15 #ifndef WEBP_UTILS_UTILS_H_
16 #define WEBP_UTILS_UTILS_H_
17
18 #ifdef HAVE_CONFIG_H
19 #include "src/webp/config.h"
20 #endif
21
22 #include <assert.h>
23
24 #include "src/webp/types.h"
25
26 #ifdef __cplusplus
27 extern "C" {
28 #endif
29
30 //------------------------------------------------------------------------------
31 // Memory allocation
32
33 // This is the maximum memory amount that libwebp will ever try to allocate.
34 #ifndef WEBP_MAX_ALLOCABLE_MEMORY
35 #if SIZE_MAX > (1ULL << 34)
36 #define WEBP_MAX_ALLOCABLE_MEMORY (1ULL << 34)
37 #else
38 // For 32-bit targets keep this below INT_MAX to avoid valgrind warnings.
39 #define WEBP_MAX_ALLOCABLE_MEMORY ((1ULL << 31) - (1 << 16))
40 #endif
41 #endif // WEBP_MAX_ALLOCABLE_MEMORY
42
CheckSizeOverflow(uint64_t size)43 static WEBP_INLINE int CheckSizeOverflow(uint64_t size) {
44 return size == (size_t)size;
45 }
46
47 // size-checking safe malloc/calloc: verify that the requested size is not too
48 // large, or return NULL. You don't need to call these for constructs like
49 // malloc(sizeof(foo)), but only if there's picture-dependent size involved
50 // somewhere (like: malloc(num_pixels * sizeof(*something))). That's why this
51 // safe malloc() borrows the signature from calloc(), pointing at the dangerous
52 // underlying multiply involved.
53 WEBP_EXTERN void* WebPSafeMalloc(uint64_t nmemb, size_t size);
54 // Note that WebPSafeCalloc() expects the second argument type to be 'size_t'
55 // in order to favor the "calloc(num_foo, sizeof(foo))" pattern.
56 WEBP_EXTERN void* WebPSafeCalloc(uint64_t nmemb, size_t size);
57
58 // Companion deallocation function to the above allocations.
59 WEBP_EXTERN void WebPSafeFree(void* const ptr);
60
61 //------------------------------------------------------------------------------
62 // Alignment
63
64 #define WEBP_ALIGN_CST 31
65 #define WEBP_ALIGN(PTR) (((uintptr_t)(PTR) + WEBP_ALIGN_CST) & \
66 ~(uintptr_t)WEBP_ALIGN_CST)
67
68 #include <string.h>
69 // memcpy() is the safe way of moving potentially unaligned 32b memory.
WebPMemToUint32(const uint8_t * const ptr)70 static WEBP_INLINE uint32_t WebPMemToUint32(const uint8_t* const ptr) {
71 uint32_t A;
72 memcpy(&A, ptr, sizeof(A));
73 return A;
74 }
75
WebPMemToInt32(const uint8_t * const ptr)76 static WEBP_INLINE int32_t WebPMemToInt32(const uint8_t* const ptr) {
77 return (int32_t)WebPMemToUint32(ptr);
78 }
79
WebPUint32ToMem(uint8_t * const ptr,uint32_t val)80 static WEBP_INLINE void WebPUint32ToMem(uint8_t* const ptr, uint32_t val) {
81 memcpy(ptr, &val, sizeof(val));
82 }
83
WebPInt32ToMem(uint8_t * const ptr,int val)84 static WEBP_INLINE void WebPInt32ToMem(uint8_t* const ptr, int val) {
85 WebPUint32ToMem(ptr, (uint32_t)val);
86 }
87
88 //------------------------------------------------------------------------------
89 // Reading/writing data.
90
91 // Read 16, 24 or 32 bits stored in little-endian order.
GetLE16(const uint8_t * const data)92 static WEBP_INLINE int GetLE16(const uint8_t* const data) {
93 return (int)(data[0] << 0) | (data[1] << 8);
94 }
95
GetLE24(const uint8_t * const data)96 static WEBP_INLINE int GetLE24(const uint8_t* const data) {
97 return GetLE16(data) | (data[2] << 16);
98 }
99
GetLE32(const uint8_t * const data)100 static WEBP_INLINE uint32_t GetLE32(const uint8_t* const data) {
101 return GetLE16(data) | ((uint32_t)GetLE16(data + 2) << 16);
102 }
103
104 // Store 16, 24 or 32 bits in little-endian order.
PutLE16(uint8_t * const data,int val)105 static WEBP_INLINE void PutLE16(uint8_t* const data, int val) {
106 assert(val < (1 << 16));
107 data[0] = (val >> 0) & 0xff;
108 data[1] = (val >> 8) & 0xff;
109 }
110
PutLE24(uint8_t * const data,int val)111 static WEBP_INLINE void PutLE24(uint8_t* const data, int val) {
112 assert(val < (1 << 24));
113 PutLE16(data, val & 0xffff);
114 data[2] = (val >> 16) & 0xff;
115 }
116
PutLE32(uint8_t * const data,uint32_t val)117 static WEBP_INLINE void PutLE32(uint8_t* const data, uint32_t val) {
118 PutLE16(data, (int)(val & 0xffff));
119 PutLE16(data + 2, (int)(val >> 16));
120 }
121
122 // use GNU builtins where available.
123 #if defined(__GNUC__) && \
124 ((__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || __GNUC__ >= 4)
125 // Returns (int)floor(log2(n)). n must be > 0.
BitsLog2Floor(uint32_t n)126 static WEBP_INLINE int BitsLog2Floor(uint32_t n) {
127 return 31 ^ __builtin_clz(n);
128 }
129 // counts the number of trailing zero
BitsCtz(uint32_t n)130 static WEBP_INLINE int BitsCtz(uint32_t n) { return __builtin_ctz(n); }
131 #elif defined(_MSC_VER) && _MSC_VER > 1310 && \
132 (defined(_M_X64) || defined(_M_IX86))
133 #include <intrin.h>
134 #pragma intrinsic(_BitScanReverse)
135 #pragma intrinsic(_BitScanForward)
136
BitsLog2Floor(uint32_t n)137 static WEBP_INLINE int BitsLog2Floor(uint32_t n) {
138 unsigned long first_set_bit; // NOLINT (runtime/int)
139 _BitScanReverse(&first_set_bit, n);
140 return first_set_bit;
141 }
BitsCtz(uint32_t n)142 static WEBP_INLINE int BitsCtz(uint32_t n) {
143 unsigned long first_set_bit; // NOLINT (runtime/int)
144 _BitScanForward(&first_set_bit, n);
145 return first_set_bit;
146 }
147 #else // default: use the (slow) C-version.
148 #define WEBP_HAVE_SLOW_CLZ_CTZ // signal that the Clz/Ctz function are slow
149 // Returns 31 ^ clz(n) = log2(n). This is the default C-implementation, either
150 // based on table or not. Can be used as fallback if clz() is not available.
151 #define WEBP_NEED_LOG_TABLE_8BIT
152 extern const uint8_t WebPLogTable8bit[256];
WebPLog2FloorC(uint32_t n)153 static WEBP_INLINE int WebPLog2FloorC(uint32_t n) {
154 int log_value = 0;
155 while (n >= 256) {
156 log_value += 8;
157 n >>= 8;
158 }
159 return log_value + WebPLogTable8bit[n];
160 }
161
BitsLog2Floor(uint32_t n)162 static WEBP_INLINE int BitsLog2Floor(uint32_t n) { return WebPLog2FloorC(n); }
163
BitsCtz(uint32_t n)164 static WEBP_INLINE int BitsCtz(uint32_t n) {
165 int i;
166 for (i = 0; i < 32; ++i, n >>= 1) {
167 if (n & 1) return i;
168 }
169 return 32;
170 }
171
172 #endif
173
174 //------------------------------------------------------------------------------
175 // Pixel copying.
176
177 struct WebPPicture;
178
179 // Copy width x height pixels from 'src' to 'dst' honoring the strides.
180 WEBP_EXTERN void WebPCopyPlane(const uint8_t* src, int src_stride,
181 uint8_t* dst, int dst_stride,
182 int width, int height);
183
184 // Copy ARGB pixels from 'src' to 'dst' honoring strides. 'src' and 'dst' are
185 // assumed to be already allocated and using ARGB data.
186 WEBP_EXTERN void WebPCopyPixels(const struct WebPPicture* const src,
187 struct WebPPicture* const dst);
188
189 //------------------------------------------------------------------------------
190 // Unique colors.
191
192 // Returns count of unique colors in 'pic', assuming pic->use_argb is true.
193 // If the unique color count is more than MAX_PALETTE_SIZE, returns
194 // MAX_PALETTE_SIZE+1.
195 // If 'palette' is not NULL and number of unique colors is less than or equal to
196 // MAX_PALETTE_SIZE, also outputs the actual unique colors into 'palette'.
197 // Note: 'palette' is assumed to be an array already allocated with at least
198 // MAX_PALETTE_SIZE elements.
199 // TODO(vrabaud) remove whenever we can break the ABI.
200 WEBP_EXTERN int WebPGetColorPalette(const struct WebPPicture* const pic,
201 uint32_t* const palette);
202
203 //------------------------------------------------------------------------------
204
205 #ifdef __cplusplus
206 } // extern "C"
207 #endif
208
209 #endif // WEBP_UTILS_UTILS_H_
210